Subtracting linear impairments for non-linear impairment digital pre-distortion error signal
First Claim
1. A process comprising:
- receiving a digital input signal;
producing a digital pre-distortion signal from the digital input signal in response to a non-linear impairment digital pre-distortion error signal;
amplifying the digital pre-distortion signal with a power amplifier to produce a radio frequency output signal;
producing from the radio frequency output signal a digital feedback signal that includes linear impairments and non-linear impairments;
separating the linear impairments from the non-linear impairments;
subtracting the linear impairments from the digital feedback signal to result in a non-linear impairment digital pre-distortion error signal; and
updating the producing a digital pre-distortion signal from the digital input signal in response to the non-linear impairment digital pre-distortion error signal from the subtracting.
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Abstract
Example embodiment of the systems and methods of linear impairment modeling to improve digital pre-distortion adaptation performance includes a DPD module that is modified during each sample by a DPD adaptation engine. A linear impairment modeling module separates the linear and non-linear errors introduced in the power amplifier. The linear impairment model is adjusted during each sample using inputs from the input signal and from a FB post processing module. The linear impairment modeling module removes the linear errors such that the DPD adaptation engine only adapts the DPD module based on the non-linear errors. This increases system stability and allows for the correction of IQ imbalance inside the linear impairment modeling, simplifying the feedback post-processing.
22 Citations
6 Claims
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1. A process comprising:
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receiving a digital input signal; producing a digital pre-distortion signal from the digital input signal in response to a non-linear impairment digital pre-distortion error signal; amplifying the digital pre-distortion signal with a power amplifier to produce a radio frequency output signal; producing from the radio frequency output signal a digital feedback signal that includes linear impairments and non-linear impairments; separating the linear impairments from the non-linear impairments; subtracting the linear impairments from the digital feedback signal to result in a non-linear impairment digital pre-distortion error signal; and updating the producing a digital pre-distortion signal from the digital input signal in response to the non-linear impairment digital pre-distortion error signal from the subtracting. - View Dependent Claims (2, 3)
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4. A system comprising:
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a digital pre-distortion module having a digital signal input, an update input, and a filtered signal output; a power amplifier having a filtered signal input coupled to the filtered signal output, and having a radio frequency signal output; a feedback post-processing module having an input coupled to the radio frequency signal output, and having a processed signal output; a linear impairment modeling module having an input coupled to the digital signal input and having a linear error signal output; an error module having an input coupled to the processed signal output, an input coupled to the linear error signal output, and a non-linear error signal output; and a digital pre-distortion adaptation engine having an input coupled to the non-linear error signal output and an output coupled to the update input. - View Dependent Claims (5, 6)
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Specification